(1) Field of the Invention
The present invention relates to a fluid lubrication bearing apparatus which supports a rotational member by a lubricating film of a fluid occurring in a bearing gap.
(2) Description of the Related Art
In recent years, fluid lubrication bearing apparatuses of this type are used as spindle motors for information appliances, for example, magnetic disk apparatus such as HDD, optical disk apparatuses such as CD-ROM, CD-R/RW, DVD-ROM/RAM, magneto-optic disk apparatuses such as MD and MO, polygon scanner motors of laser beam printer (LBP), and as small motors for other apparatuses, utilizing their excellent rotational accuracy, high rotational speed, silence and other properties.
For example, in a fluid lubrication bearing apparatus integrated in a spindle motor of disk drive units such as HDD, a radial bearing portion which supports a shaft member in the radial direction and a thrust bearing portion which supports the shaft member in the thrust direction are both sometimes constituted of hydrodynamic bearings. An example known of a radial bearing portion in such fluid lubrication bearing apparatuses includes that comprising hydrodynamic pressure grooves formed as a hydrodynamic pressure producing part on one of the inner circumferential surface of the bearing sleeve and the outer circumferential surface of the shaft member opposed to this and a radial bearing gap formed between the two surfaces (for example, refer to Japanese Unexamined Patent Publication No. 2003-239951).
The bearing sleeve constituting the above bearing is fixed at a predetermined position on the inner periphery of a housing. A common means for fixing the bearing sleeve on the inner periphery of the housing is adhesion using an adhesive. The procedure of such a means comprises the steps of, for example, applying an adhesive on the inner circumferential surface of the housing in advance, inserting the bearing sleeve at the inner circumferential surface of the housing, positioning at a predetermined position, and then curing the adhesive.
At this time, if an excessive amount of the adhesive is provided, while the bearing sleeve is being moved to a predetermined position after being inserted at the inner circumferential surface of the housing, an excess of the adhesive may overflow to the front of the bearing sleeve in the direction of movement, which may adversely affect the positioning and the bearing performance of the bearing sleeve. To prevent the adhesive from overflowing, for example, a concave shaped adhesive reservoir is sometimes formed on the inner circumferential surface of the housing (for example, refer to Japanese Unexamined Patent Publication No. 2004-176816).